Ecological studies have widely demonstrated that plant diversity positively affects ecosystem functioning and ability to respond to changing conditions (Hooper & Vitousek, 1997;Isbell et al., 2011). As most flowering plants are pollinated by animals, plant-pollinator interactions play a significant role in the health of terrestrial ecosystems (Klein et al., 2007;Ollerton et al., 2011). The stable coexistence of multiple species in plant communities requires explanation, as many plants compete for resources such as water, light, soil nutrients and pollinators (Barot & Gignoux, 2004;Rathcke, 1983). Various factors can contribute to plant coexistence (Wilson, 2011). Flowering plants may mitigate competition, for example, by forming spatial patches (Tilman, 1982), by temporal heterogeneity in resource consumption (Questad & Foster, 2008) or by pollination niche partitioning (Benadi, 2015;Pauw, 2013). Recent theoretical papers have integrated the foraging behaviour of pollinators with plant community dynamics and discussed factors that could allow plant coexistence: adaptive foraging behaviour of individual pollinators (Revilla & KĹivan, 2016;Song & Feldman, 2014); high immigration rate of a rare plant species (Song & Feldman, 2014); pollen carryover (Montgomery, 2009;Song & Feldman, 2014); and dynamics of floral reward production and limited information of pollinators regarding reward distribution (Benadi & Gegear, 2018).The effects of pollinators' foraging behaviour on plant coexistence may also be mediated by floral traits, such as complex flower morphology. Morphological complexity (Figure 1) can have conflicting effects on the plant and on the pollinator during a visit: it tends to be beneficial for the plant, since it encourages longer visits and thus potentially increased pollen transfer (Harder, 1990;Manetas &